Mr. Brown's class is collecting books for a book drive. They started with 2 books. On the first day, they had 6 books. On the second day they had 18 books. Write an equation that models this situation.

A)
y = 4x + 2


B)
y = 2(3)x


C)
y = 3x + 2


D)
y = x2 + 2